The present invention is directed to heating, ventilating and air conditioning systems, and more particularly, to improvements in heating, ventilating and air conditioning system testing.
Heating, ventilating and air conditioning (HVAC) systems have a number of possible system operating states, including heat pump, heat, cool, economizer, defrost, fan, and emergency heat. Each of these states can have several stages, such as might occur in a cooling system with more than one compressor, in a heating system with several heat stages, or in a heat pump system with auxiliary heat. Additionally each state can have variations depending upon the energy source used for air temperature control, i.e. electric, gas, or heat pump.
HVAC systems are tested by sequentially activating all relevant system states including each relevant stage, and all relevant variations. The subsequent operation of each state of the HVAC system is then observed for deviation from acceptable operation. The test capability in some previous systems provides an automatic, sequential activation of all possible refrigeration system states. Other systems provide a stepped, sequential activation of all possible refrigeration system states whenever an operator takes some positive action to tell the controller to move to the next state in the sequence. Still other systems allow an operator to manually select a single specific state for observation.
Each of these types of test capabilities has advantages and disadvantages. Manual test selection has the advantage that a sophisticated technician can initiate a particular test and observe the results without requiring the sophisticated technician to step through a sequence of states. The manual test has the disadvantage that an unsophisticated user may have neither the skill nor the knowledge to activate the operating mode, particularly where the system requires the use of a piece of equipment such as a resistor box to manually select an operating mode. Stepped test selection has the advantage that an unsophisticated user can operate the mode without the use of sophisticated equipment. Automatic test selection has the advantage that it need only be turned on, allowing a very unsophisticated user to monitor the operation of the refrigeration system. Automatic test selection has the disadvantage that the user cannot control the selection or timing of the sequence. Stepped and automatic test selection have the further disadvantage that a sophisticated user or technician may be frustrated at following the predetermined and mandatory sequence of states when the user or technician only desires to monitor one specific state.